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Imagine trying to ride your sport bike with your eyes closed. How far do you think you'd get? Well, sometimes conditions are such that it's almost as if you were riding with your eyes partly closed. Even if your vision is so sharp that you can count the hairs in a gnat's eyebrow at 20 feet, you may not always see the way you should.

Although the human eye is often compared to a camera, it's far more sophisticated than the finest camera. Unlike the camera, the eye can see only a narrow focus zone clearly. That's why it constantly shifts-as many as 10 times a second-when it views something. If it weren't for this panoramic effect, you would have tunnel vision.

Because the eyes need constant stimulation, staring actually causes a loss in sharpness. The longer you fix your gaze on something, the less you see. Contributing to the danger is the fact that peripheral vision decreases dramatically when you're staring until you can see only in a hazy narrow zone directly ahead.

We depend heavily on peripheral vision to keep us informed as to what's going on around us. When something catches our attention peripherally, we then zoom in on it with central or "foveal" vision. Instead of straining to see something, use what the Zen masters call "soft eyes": View everything with a relaxed but keen focus. Keep your line of sight moving; never focus on anything for more than two seconds. This is especially true when you're riding at high speeds, or even at moderate speeds in heavy traffic.

At first it might seem logical to keep your head aligned with your body when you're leaned over for a high-speed sweeper. Wrong. Keep in mind that your eyes are also an important part of your body's balance systems. In fact, some 20 percent of the eyes' nerves hook up to the brain's body-balance centers. This means that the eyes must be vertically oriented to the horizon, or else they'll send confusing information to the brain. Another advantage of keeping your head level is that it allows you to see farther along the curve.

Whether you have 20/20 acuity or wear glasses, you can improve your vision to some degree. The following tests/exercises can help you determine your visual weaknesses so you can effect some degree of improvement.

Scanning: Any activity where you have to track a moving object, such as tennis, racquetball or Ping-Pong, is excellent for enhancing scanning ability. Video games are also effective for developing eye motility. Of course, motorcycling provides the opportunity to keep those eyeballs in motion, as you scan in all directions, from near to far. The faster you ride, the more critical scanning becomes, because your zone of effective vision shrinks.

It's important to move only your eyes. Moving your head blurs your field of vision. Again, to prevent staring, never hold your line of sight for longer than two seconds.

An important part of scanning is being able to focus on objects at varying distances. If you're nearsighted or farsighted, you know about this.

A simple exercise for improving focus is to cut out a letter from a newspaper headline and stick it on a wall at eye level. Then cut out a small classified ad. Stand eight to 10 feet from the wall, hold the classified ad up at eye level and read it, bringing it closer to your face until the letters blur. Now switch your focus to the letter on the wall. Practicing this technique will improve your focus shift from near to far.

Peripheral Vision: The need for good peripheral vision-seeing sideways while looking ahead-is another critical aspect of cycle sight. You depend on "side sight" to detect danger that lies outside your narrow zone of central vision.

A simple test and exercise for peripheral vision is to hold a pencil or similar object in each hand and extend your arms out to the sides. If you have good peripheral vision, you should be able to see both objects from the corners of your eyes while looking directly ahead. With practice you can widen your field of view.

Depth perception: Depth perception-visually computing your distance from something-is also critical. Test and exercise depth perception as follows: Thread a four- to five-foot section of string through three differently colored buttons or beads, secured and spaced equidistantly; tie one end of the string to something at eye level; then pull the string tautly and hold the loose end up to your nose so that the nearest button is no closer than 12 inches from your face. If your eyes are working together, you should see a "V" when you focus on the first button; two strings should seem to converge at the button. If your depth perception is off, the V will appear in front of or behind the button. Repeat this process with the second and third buttons. This exercise teaches your eyes to work together.

You might consider looking into a sports-vision program to improve your eyesight, and remember: Keep those eyes moving.

This article originally appeared in the April 1995 issue of Sport Rider